Printable batteries

Ultrathin electronic devices can be built using a special inkjet printer that squirts fine layers of complex compounds instead of ink. When the compounds dry, they leave behind sheer metallic films, which in the right combination could act as thermometers, light sensors, even computer chips. So why haven’t you seen these gadgets yet? In part because they are hard to power: even the smallest lithium-ion watch battery is too bulky.

The solution is to print batteries too. This year, a research team at the Fraunhofer Research Institution for Electronic Nano Systems revealed a 0.6-millimeter-thick battery.

It consists of a stack of metal pastes that act as anode, cathode and electrolyte, bound on top and bottom by carbon layers that collect electricity and deliver it to the attached device. This product can be built right into the device it’s powering, as part of the production process, so there’s no need for an additional assembly line. And the battery can be made as large or as small as needed, simply by printing more of it. The list of possible applications is endless — from bandages that release medication when they sense an increase in body temperature to wallpaper that changes color at the flick of a switch.

from the NY Times Year in Ideas